Project Summary Acute alcohol abuse and alcohol dependence create an enormous burden on individuals, families and society through health and socioeconomic impacts. Binge drinking episodes and long-term alcohol consumption result in the increased incidence of multiple diseases, accompanied by cellular damage and tissue injury. Differential sensitivity to alcohol can result in differences in drinking behavior and variation in alcohol toxicity at the cellular and tissue levels. Understanding and treating the physical consequences of alcohol abuse requires identification of those factors affecting differential alcohol sensitivity and alcohol toxicity and the cellular and molecular mechanisms through which these factors modulate responses to alcohol. Endogenous circadian clocks allow organisms to optimize behavioral and physiological processes relative to the time of day. Recent research in several model systems has shown clear interactions between the endogenous circadian clock and differential sensitivity and toxicity to alcohol, however, the mechanisms through which this occurs remain unclear. There exists a critical need for studies examining the interactions of the circadian clock with physiological and metabolic responses to alcohol to be performed in a system that allows for the molecular mechanisms underlying this interaction to be identified. Drosophila has long been recognized as a superior model system for studies of the core functioning of the circadian clock and the circadian regulation of metabolic, physiological and behavioral outputs. Drosophila also has been established as a model system for the study of alcohol response behaviors and their underlying mechanisms as the response to alcohol appears remarkably conserved between flies and humans. Our preliminary research indicates that the circadian system is tightly intertwined with acute sensitivity to alcohol in Drosophila. Te objectives of this application focus on identifying the molecular mechanisms through which the circadian clock modulates alcohol sensitivity and identifying the impact of circadian modulation on alcohol-induced cellular damage. The tremendous number of available mutants and transgenic techniques for specific gene expression combined with fast generation time and the practicality of animal maintenance have made Drosophila a superb system for the identification of genes involved in complex behaviors. Given the evolutionarily conserved mechanisms underlying circadian oscillators as well as the high degree of conservation in signaling pathways affected by alcohol, the experimental results from this research in Drosophila will be broadly applicable across species. Thus, these experiments will provide a foundation for the future development of therapeutic drugs and treatments for prevention of the adverse health effects associated with alcohol abuse.